In light of the current national concern over terrorism and mass shootings in schools and other institutional settings, a relatively standardized procedure for responding to a security threat in a school building has been developed: the “lockdown”, in which teachers essentially lock themselves and their students in their rooms to deter invaders and await help.
A problem with the lockdown procedure is that fire safety codes typically mandate the use of outward-opening doors, and the use of locks that are key-locked from outside the room and released by simply turning the doorknob from inside the room. These fire safety measures interfere with the speed and security of the lockdown procedure. The teacher must open the classroom door, step outside, and key the lock, exposing himself and the classroom to danger; a panicky student can easily unlock the door from the inside; and if the door has the typical glass window, a gunman can break the glass, reach inside, and unlock the door by turning the inside doorknob.